Please help. Need advice.

Please help. Need advice.

Purchased a note 3 from eBay. Seller never disclosed the phone was rooted with safestrap. Not very happy about that. Phone is fine until I wanted to update to 4.4. It would not install. Was getting an error. It would download but failed to install.
So I Un rooted the phone through super user. Than tried to root again thorough Kinko and it failed to root several times. Why?
So now I'm stuck. Phone works fine but I would like to set it back to stock and take safestrap off so I can sell it because I bought another one.
Is there anyone that can give me step by step instructions on how to get this phone to factory settings like it did out of the box. Because now when it boots it goes thorough safestrap, it's not rooted and it won't let me root for some reason. Plus I can't upgrade to 4.4. What a mess. Can anyone help? Thanks